p {
  width: 800px;
  height: 300px;
  background: -webkit-linear-gradient(-30deg, red 30px, orange 150px, yellow 280px, pink 500px, blue);
  /*-webkit-background-clip: text;*/
  color: rgba(255, 255, 255, 0.3);
  text-align: center;
  line-height: 300px;
  font-size: 100px;
  transition: 4s;
  cursor: pointer;
}

p:hover {
  background-position: 400px;
}